Pulmonary oxalosis is a very rare pseudotumoral lesion; it is often secondary to an aspergillus infection. Oxalic acid (C(2)H(2)O(4)) is a mycotoxin released by Aspergillus niger and sometimes by several other fungi, including A flavus and A fumigatus. We report a case of a 69 year old man, with previous history of pulmonary tuberculosis, followed for recurrent hemoptysis. On the chest radiography, the right upper lobe lung showed a cavitary lesion with thick and irregular walls and a dense material that suggested a pulmonary aspergilloma. Microscopically, it was a pulmonary oxalosis associated with chronic necrotising pulmonary aspergillosis. Our aim is to discuss the epidemiological characteristics, the diagnosis and the histogenesis of this unusual lesion.